I study the combination of two French discourse markers, mais (‹but›) and enfin (‹well›, ‹finally›, etc.) in spoken and written language. Combinatorial constraints are highlighted at two levels: first, I propose a fine-grained analysis of the semantic and pragmatic values of both items and of their compatibility; second, I use association measures in order to test the strength of attraction between mais and enfin. Such a qualitative and quantitative approach leads to the idea that when mais and enfin are contiguous, they function as a collostruction, whose compositional status requires further investigations to be better understood.